Saponified products of ethylene-vinyl acetate copolymers (hereafter referred to as EVOH) are widely known as melt-formable thermoplastic resins that are excellent in gas barrier properties, oil resistance, solvent resistance, flavor retention properties, etc. and have been used for films, sheets, containers, etc. in various wrapping arts.
However, EVOH has some disadvantages, such as it is rigid and fragile and lacks flexibility so that EVOH is scarcely used alone but has mainly been used in laminates with other thermoplastic resins. But cracks and pinholes are still formed in the EVOH layer because of violent vibrations, for example, due to transportation, flexural fatigue, etc. and, therefore, the excellent gas barrier properties cannot be retained.